The invention relates to a GPS (Global Positioning System) receiver module for receiving GPS signals and for determining position data therefrom, and to a dual band antenna for such a receiver module.
As is well-known, GPS signals serve for global position finding and navigation and are emitted by a network of satellites totaling 24 satellites, which circle the Earth on different orbits, so that at least five satellites are visible at any point on the Earth""s surface at any one time.
The position finding is based on the principle of a transit time measurement of signals, which are modulated upon electromagnetic carrier waves with a carrier frequency of 1575.42 MHz. The signals emitted by the satellites are time-synchronized and consist of two parts. A first part contains the respective satellite positions and the time with which a clock in the GPS receiver is synchronized. From the second part, the GPS receiver determines the orbit data of the satellites that can be received at that instant. The position of the GPS receiver is calculated from these.
GPS receiver modules which contain the receiving and evaluation electronics needed for this are already known. Depending on the purpose for which the module is intended, the position data are either delivered to an interface for further processing in other units, or the module has an integral display unit for the position data. Modules of this type are built into mobile and fixed navigation equipment for applications in aviation, shipping and road traffic.
Since GPS modules are becoming ever smaller and less expensive, efforts are also being made to fit these into appliances that do not typically serve for navigation purposes, such as mobile telephones, portable computers and wristwatches, for example. The integration of a GPS module into such an appliance, however, in many cases also calls for extensive intervention in the electronics of the appliance itself where, for example, inputs to the GPS module are to be made via a keypad of the appliance or position data are to be shown on a display of the appliance.
An object of the invention is therefore to provide remedies in these instances and to identify a more simple way of connecting GPS receiver modules to other electronic equipment.
In particular, the invention is intended to create a GPS receiver module, which is capable of interacting with a multiplicity of other appliances.
Finally, the invention is also intended to create an integrated GPS receiver module, which contains all units needed for reception and evaluation, and for communication with one of the aforementioned appliances.
In addition, the invention is intended to create a dual band antenna, which is particularly suited to integration with such a GPS receiver module and by means of which it is not only possible to receive the GPS signals but also to establish a communications link with the said appliances.
This object is achieved by a GPS receiver module, which as claimed in claim 1 is characterized by a communications sub-module, to which the position data determined can be fed and by means of which these data can be converted into a format suitable for transmission to an external appliance.
One advantage of this solution is that it permits the use of GPS receiver modules with those external appliances that have a corresponding interface for this format.
As claimed in claim 2, a communications module to the Bluetooth standard is particularly advantageous in this respect, since more and more appliances are being equipped as standard with a Bluetooth interface.
The embodiment as claimed in claim 3 has the advantage that the GPS receiver module can receive not only GPS signals but also data from other external appliances and can, where appropriate, also be correspondingly controlled thereby.
The embodiment as claimed in claim 4 lends itself to an exceptional degree of miniaturization, whilst the embodiments as claimed in claims 5 and 6 also permit line transmission of data between the GPS receiver module and an external appliance, that does not have an interface to the Bluetooth standard.
As claimed in claim 7, a dual band antenna, which is particularly well-suited to integration with the GPS receiver module, is characterized by the following features: a ceramic substrate with a first resonant conductor path structure and a second resonant conductor path structure, which are connected to a common feed, the length of the first conductor path structure corresponding to approximately half the wavelength of a BT signal in the substrate and the length of second conductor path structure to approximately half the wavelength of a GPS signal in the substrate.
At this point it should be mentioned that although EP 1 079 463 discloses xe2x80x9casymmetrical dipole antennasxe2x80x9d, which are intended for service in the GPS or BT band, these are microstrip transmission line antennas, in which a metallic surface forming a reference potential (generally on the back of the substrate) must be present. Since the antennas according to the invention work on the principle of wire antennas, however, this prior art is obviously not relevant.